More than a third of high school seniors said they have vaped in the past year — up nearly 10 percentage points from the previous year. The dramatic jump comes despite efforts by public health officials, educators and lawmakers to reverse the e-cigarette trend among youths, including a recent proposal to ban retail sales of flavored tobacco products in California.

As more parents turn to medical marijuana to treat their sick children, a handful of states have changed the rules to allow them to administer the drug on campus. California is considering it — at the possible risk of losing federal funding.

Suffering Americans seek medical marijuana as an alternative to opioids and other powerful pharmaceuticals. Though legal in 29 states, some doctors say the lack of strong data makes it hard to recommend.

Some mothers who smoke pot see it as a harmless remedy for everything from pain to postpartum depression. But doctors say the active ingredients in marijuana can be passed onto the baby and may affect developing nervous systems.